Let us for the moment leave chads, whether pregnant or dimpled, twisting in the wind. The supreme court of Florida is welcome to them. Something rather more serious - no, literally apocalyptic - lurks behind these frenzied American revels; something that, this week links Palm Beach and the Hague. A simple question: can democracy save the world?

Guardian readers know that teams from 180 countries have gathered in Holland to try, one more time, to secure an agreement which reduces the greenhouse gas emissions that threaten the future of our globally warmed globe. Three years ago, in Kyoto, the leaders of those 180 countries solemnly promised to cut these emissions. They have not, however, been cut: they have risen.

Even Kyoto, with the modest reductions it set, hasn't held. And, in particular, the US - with 5% of world population and 25% of emissions - has not kept to its word or the puny, insufficient targets it accepted in Japan. Unless the new rulers in Pennsylvania Avenue, whoever they turn out to be, can be persuaded to wake up and shape up, then we might as well not bother. A world environment policy without the polluter-in-chief is a hole in the head and a hole in the ozone layer. There will be no more important conference - for America or any of us - this year.

Guardian readers know this because the Guardian reports it. American readers are less well served. In the US you may wade through dead forests of newsprint this morning without finding mention of the Hague. It might as well be happening on another planet, not the other side of our planet. And, anyway, George W Bush says he does not believe in global warming. He doesn't think it exists. Al Gore believes all right, yet he hasn't managed, over eight years in power, to do much about it.

Hang on though! Isn't there, at last, a strong, growing American Green party now? And didn't it, in many ways, shape the whole presidential debate, raising causes that others feared to touch? Ralph Nader made the death penalty and privatised prisons and failed drug wars real issues. He put his old enemy, corporate power, in the firing line. It would have been a far poorer election without him.

The thing that haunts me, 12 days on, is that it would also have been a different election. Without the irate grey panthers of Palm Beach waving their butterfly ballots, George W would already be far into his triumphant transition - and the clear divide between his victory or defeat was, and is, Nader's Green vote. We're talking 80,000-plus, not a frail 930. Nader, taking Florida Democrat votes quite disproportionately, filled out Bush's White House pass.

Democrat bosses are bitter about that, but Nader just shrugs. Without him, he says, there was only a choice of two evils. Evil, whatever its shade, is still evil. President Gore would be an evil, too. "Al Gore lost this election for Al Gore." Nader, with his calm fury and idealism, brought in hundreds of thousands of young people turned off by standard campaigning. He was an energising force (and a prophet his supporters keep comparing with Gandhi).

Fair enough. But I went to Nader's last great Washington rally, almost as the polls opened a fortnight ago, and sat through four hours of oratory and ambition. I did not once hear the words "global warming" uttered. Nor "ozone layer". These were Green warriors who seemed more anxious to talk at length about statehood for the district of Columbia. These were environmentalists reserving their biggest cheers for legalising pot smoking.

Now, of course, Nader does have the requisite policies somewhere in the greenhouse. Leaf through his position papers and you'll find him endorsing the standard Ozone Action programme and shredding Gore as an "environment poseur" playing a cynical con game. But he made precious little of it, one brick amongst many, at the close. The "uncompromising political force" he aimed to create was more interested in enfranchising Washington voters.

Which is why I worry so deeply about what democracy can address, and what it can achieve, in a true environmental crisis.

There are 90 or so Green parties around the world. Some rise and rise - to a share of government in Germany (where they embrace the European federal state). Some, like our own Greens, rise and fall again. There is no pattern to the way they bring their urgent message, the most urgent message of all. The end-of-the-world message. They don't know whether to be part of the process, or the heart of the process or standing outside it, proclaiming doom.

"Where were they when the petrol tanks ran dry?" one Labour cabinet minister asked me privately the other day. Strangely silent, he thought. When the case for higher fuel taxes had to be made, he didn't hear much cheeping from the British Greens. They only surfaced to denounce Tony Blair's big environmental speech as - of course - not enough.

There must, I think, be a parallel staring at boots in America today. Ralph Nader's presidential run, in all likelihood, will cost Gore the White House. That is not a value judgment, but a statistical one. If that's the way the next few days turn out, then there will be no action of any meaningful kind through Bush's Oval Office years. The pollution of the US, like the pollution of Texas, will proceed without let or hindrance. The failure of the Hague talks is foredoomed.

How do you trade off four or eight years of that against vote-splitting and future party building? Where is the equation between some small progress now and no progress at all? These are terrible conundrums, but they can be put in hard terms.

Bush and Cheney - as they would - want to license oil drilling in the Arctic National Wildlife Refuge, America's last great wilderness. They'll get that through Congress. Why rely on Arab oil, when you've got more of your own? Gore - for all his trimmings - is committed to stop that. If I were a porcupine caribou in that last great wilderness, what would I vote for - death today or life tomorrow?

Here's the inescapable dilemma. If profligate energy use, low petrol prices, the whole bent of this consumer society, is ruining the earth today, then it needs an answer today. There is no tomorrow if you don't talk greenhouse gases today. But the voters don't want to listen and even prophet-politicians like Nader who seek their vote don't tell them in terms. Less petrol at a greater price? Forget it. When gun holders vote Bush, as they did, to hang on to their guns, what chance that car owners will vote to make their own lives more difficult?